1. Field of the Invention
The present invention relates to a thermoplastic resin composition having antistatic properties and conductivity, and a heat-resistant tray for IC obtained by molding the same.
2. Description of the Related Art
As trays for carrying IC parts (chips), there have been conventionally used vinyl chloride resins, polystyrene resins, polypropylene resins and the like to which conductivity and antistatic properties had been imparted.
In mounting IC parts on a printed board by soldering, water vapor is generated in the IC parts by soldering heat, such that blistering and cracking can occur and injure the IC parts if a package of the IC parts is wet, therefore, it is necessary to remove moisture at a temperature of 120.degree. C. to 150.degree. C. before mounting. Conventionally, it has been necessary to transfer IC parts from a carrying tray to on an aluminum die-cast tray in this drying process. However, recently, such a tray having a carrying property and drying property together has been developed using a modified polyphenylene ether resin endowed with conductivity or antistatic properties, and has pervaded. However, when the time needed for drying of IC parts is shortened, a high temperature of for example 150.degree. C. or more is required, and regarding a tray composed of modified polyphenylene ether resin, no tray made thereof has heretofore been satisfactory in the points of heat-resistance, minimizing warping of a molded article, molding processability and the like.
On the other hand, an aromatic polycarbonate resin has excellent mechanical strength and dimensional accuracy, however, it has a heat-resistant critical temperature of at most 150.degree. C. Then, for the purpose of improving heat- resistance and the like, various thermoplastic resin compositions obtained by mixing aromatic polycarbonate resins with aromatic polysulfone resins have been disclosed.
For example, Japanese Patent Application Publication (JP-B) No. 45-39181 discloses a production of a composition that is excellent in heat-resistance and mechanical properties by mixing an aromatic polysulfone resin with an aromatic polycarbonate resin.
Further, JP-B No. 49-13855 describes that compositions composed of aromatic polysulfone resins and aromatic polycarbonate resins have more excellent heat-resistance and mechanical properties as compared with ABS resins.
Moreover, in Japanese Patent Application Laid-Open (JP-A) No. 54-28361, there is disclosed that a composition composed of an aromatic polycarbonate resin and aromatic polysulfone resin having a weight-average molecular weight of over 60,000 has improved chemical resistance and deflection temperature under load as compared with other various resins.
Furthermore, JP-A No. 60-51739 discloses that a composition composed of an aromatic polysulfone resin and an aromatic polycarbonate resin is excellent in mechanical properties and has improved chemical-resistance.
However, the above-described compositions often have unsatisfactory physical properties, since aromatic polycarbonate resins inhibit excellent physical properties represented by heat-resistance originally owned by aromatic polysulfone resins. Further, the above-described publications have no description regarding use of the compositions in he at-resis tant trays for IC.
In addition, for imparting antistatic property or conductivity required in heat-resistant trays for IC, a carbon fiber or conductive carbon black is generally compounded, however, this causes problems in that the resulting molded article generates an anisotropy in surface resistance, and the surface resistance of the molded article varies due to a slight change in the compounding amount, and the like.
An object of the present invention is to provide a thermoplastic resin composition having excellent heat-resistance and molding properties, and having antistatic property or conductivity, and a heat-resistant tray for IC obtained by molding the same.